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/*
* Copyright 2014 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package org.glowroot.shaded.netty.util.internal;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
public abstract class MpscLinkedQueueNode {
@SuppressWarnings("rawtypes")
private static final AtomicReferenceFieldUpdater nextUpdater;
static {
@SuppressWarnings("rawtypes")
AtomicReferenceFieldUpdater u;
u = PlatformDependent.newAtomicReferenceFieldUpdater(MpscLinkedQueueNode.class, "next");
if (u == null) {
u = AtomicReferenceFieldUpdater.newUpdater(MpscLinkedQueueNode.class, MpscLinkedQueueNode.class, "next");
}
nextUpdater = u;
}
@SuppressWarnings("unused")
private volatile MpscLinkedQueueNode next;
final MpscLinkedQueueNode next() {
return next;
}
final void setNext(final MpscLinkedQueueNode newNext) {
// Similar to 'next = newNext', but slightly faster (storestore vs loadstore)
// See: http://robsjava.blogspot.com/2013/06/a-faster-volatile.html
nextUpdater.lazySet(this, newNext);
}
public abstract T value();
/**
* Sets the element this node contains to {@code null} so that the node can be used as a tombstone.
*/
protected T clearMaybe() {
return value();
}
/**
* Unlink to allow GC'ed
*/
void unlink() {
setNext(null);
}
}